The invention has applications in the aeronautics, such as in the field related to the safety of the members of the crew of an aircraft, including the pilots. In the aeronautics field, particularly for aircraft that transport passengers, there is a door that separates the cockpit from the passenger cabin. This separation door is secured in order to protect the pilots from any attack by one or more passengers, particularly a terrorist attack.
In order to accomplish this, the separation door is reinforced. It is also locked. Locking may occur automatically as soon as the aircraft leaves the parking area or as soon as the access doors to the passenger cabin are closed. Furthermore, to make the door more bullet-proof, the door frame is reinforced, which makes it possible to prevent a passenger from firing bullets through the gap between the door and its frame.
FIG. 1 is an overview of the front of an aircraft 1 equipped with a standard separation door 5 between the passenger cabin 3 and the cockpit 2 of the aircraft. The cockpit 2 is intended to accommodate at least part of the aircraft's flight crew. The cabin 3 is intended to accommodate the aircraft's passengers and, potentially, part of the flight crew.
The separation door 5 is positioned in a partition 4 separating the cockpit 2 and the cabin 3. The separation door 5 includes a cockpit-side face 5a and a cabin-side face 5b. The door 5 is placed perpendicular to the surface of the aircraft floor. The door 5 is mounted on a door frame 7 by means of hinges 6, aligned along an axis perpendicular to the surface of the floor. The hinges 6 are generally located on the cockpit side 5b of the door so that the passengers cannot access them from the cabin. The door frame 7 may comprise a stop face that partially covers the cabin side 5a of the door when this door is closed, that is, when it blocks passage between the cockpit and the cabin. The door frame 7 is produced so that there are no gaps between the door 5 and this frame 7 so that an armed person located in the cabin 3 of the aircraft cannot fire bullets through these gaps.
In the door configuration just described, the door 5 and the door frame 7 only allow the door to open toward the cockpit 2. It is understood that the door 5 may also be mounted on its frame 7 in the opposite manner or differently, for certain applications.
An example of this type of secured door is described in patent application FR-A-2 848 179. This type of cockpit door is designed to be compatible with the security measures currently aimed at reinforcing the safety of the flight crew installed in the cockpit. This door is also adapted to withstand depressurization that may occur inside the aircraft and, more specifically, inside the aircraft cabin.
To satisfy the current safety regulations, this separation door is locked as soon as the aircraft leaves the parking area and for the entire duration of the flight. An example of a standard locking system is shown in FIG. 2. This locking system comprises a set of electric strikers 12 or bolts installed in the side of the door, that is, in the edge of the door or near the edge of the door. In locked position, these bolts are inserted in tumblers mounted in the door frame 7 or in openings in the frame 7 adapted to received these bolts. This set of bolts is controlled electrically. More specifically, these electric bolts are continuously powered to ensure that the door is locked. When the electric power supply is cut off, the bolts slide toward an unlocked position. The door is then unlocked.
This locking system therefore locks the door 5 electrically. The flight crew installed in the cockpit 2, hereinafter called the cockpit crew, can open the door, that is, unlock the door by means of a manual unlocking control 8, for example a control lever. This manual control 8, hereinafter called the lever, is connected to a control unit 10 of the door that electronically controls the locking and unlocking of the door 5. If the flight crew installed in the cabin 3 of the aircraft, hereinafter called the cabin crew, needs to enter the cockpit, for example to bring the cockpit crew a meal, this cabin crew has the option of entering a code on an alphanumerical keypad 9 installed in the cabin 3 near the door 5. This code controls a buzzer 11 installed in the cockpit 2, which issues a sound signal. This buzzer indicates to the cockpit crew that a member of the cabin crew is requesting access to the cockpit. The cockpit crew may then decide to open the door 5; to do so, they activate the lever 8, which, through the control unit 10, cuts off the power to the locking system, unlocking the door. Aside from this buzzer, the cockpit crew may choose whether to activate the unlocking control lever or not.
If the cockpit crew is unable to react to unlock the door, for example, if the cockpit crew has lost consciousness, it is important for the cabin crew to be able to rescue the cockpit crew. To do so, the alphanumerical keyboard 9 located near the door 5 allows the cabin crew, by means of a specific procedure, to unlock the separation door directly, after a certain time interval, 30 seconds, for example, thus allowing the cabin crew to rescue the cockpit crew. This specific procedure is such that it cannot be performed by the passengers in the cabin and, more particularly, by terrorists.
FIG. 3 shows an electrical diagram of the locking systems of FIG. 2. This electrical diagram shows the different connections between the different components of the system. The control unit 10 is connected to the buzzer 11 and to the alphanumerical keypad 9. The control unit 10 is also connected to all of the bolts 12 and to the unlocking lever 8. The control unit 10 is also connected to a breaker 13 that ensures the electrical safety of the system. It is thus understood that the control unit 10 manages the transmission of the sound signal to the buzzer 11. The control unit 10 also controls the unlocking of all the bolts 12 based on the signals received from the manual controls, namely the lever 8 and the keypad 9, by transmitting electrical power to all of the bolts or by cutting off this electrical power. This electrical power cutoff is therefore controlled only by the control unit 10 based on an order received from the control lever 8 or from the alphanumerical keypad 9.
However, if the aircraft crashes, it is possible that certain deformations of the door or of the door frames may prevent the cabin crew from unlocking the door using the keypad. In this case, it is necessary to wait for the specialized ground response teams to destroy the door using cutting tools such as axes to enter the cockpit and rescue the cockpit crew, which may take a relatively long period of time. Now, it has been shown that an aircraft may catch fire relatively quickly (in around a few minutes) after a crash. The time necessary for the specialized response teams to respond is, in this case, too long to allow the cockpit crew to get out in time.